Johnson & Johnson claims that the powder is made from a natural mineral named Talc. It contains oxygen, hydrogen, silicon, and magnesium. In simple words, talc is a hydrous magnesium silicate, used in cosmetics and personal care products, as it is a good absorbent of moisture.
The only reason why cancer came into the limelight is that Asbestos is also released from where it is extracted. It can be dangerous and life-threatening for the body. During the mining of talc, there is a high risk of getting mica, which could be harmful.